1. Technical Field
This invention relates to systems and devices for filtering stack gases to remove dry solid waste material therefrom.
2. Description of the Prior Art
Prior devices and systems of this type may be seen in U.S. Pat. Nos. 2,843,217, 3,375,638, 3,615,248, 3,686,832 and 4,081,255.
In the U.S. Pat. Nos. 2,843,217 and 3,615,248, rotatable drums incorporating a plurality of circumferentially spaced filter units are revolved into and out of a flue gas path.
In U.S. Pat. No. 2,843,217, the flue gas is passed through two of the circumferentially spaced filters simultaneously, and in U.S. Pat. No. 3,615,249, the flue gas path is through one of the circumferentially spaced filters.
In U.S. Pat. No. 3,375,638, the filters take the from of electrostatically charged belts in spaced relation in the flue gas path with means for moving the belts into and out of the flue gas path.
In U.S. Pat. No. 3,686,832, a horizontally disposed drum having a plurality of filter elements positioned radially about the core thereof are rotated around the flue gas path with valves controlling the direction of the flue gas through the several filters in the horizontally disposed drum.
In U.S. Pat. No. 4,081,255, a track system is provided for moving a carriage carrying two horizontally spaced filter containers into and out of a vertical flue gas path. The present invention provides a housing positioned in the flue gas path and defining a central passageway therethrough and a plurality of chambers on either side thereof with a plurality of dual filter elements in the form of screened panels positioned vertically in the housing and slidable sidewardly so that one screen in each panel is always positioned in the central passageway in a filtering position with respect to the flue gas passing therethrough. The other screen in each of the screen panels forming the dual filter elements is always in one of the chambers at the sides of the central passageway where it is subjected to a cleaning action as by communication with a vacuum system arranged to move air through the screen element in a reverse direction with respect to the flue gas path. The reciprocal dual filter elements actuate valves controlling the communication of the respective chambers in which they are alternately positioned with the vacuum system.